Sewage Lagoon and Lift Station Management: A Practical Guide to Aeration, Bioaugmentation and Automated Dosing

Why sewage lagoons and lift stations lose performance

Wastewater systems rarely receive a constant load. Daily flow cycles, industrial discharges, septage inputs, stormwater infiltration, seasonal population changes and unusually strong waste can alter hydraulic and organic loading. A lagoon that performs adequately under average conditions may become stressed when incoming biodegradable material consumes oxygen faster than aeration and natural reaeration can replace it. Shorter effective retention time can also reduce the opportunity for biological treatment and settling.

Temperature, pH, nutrient balance and mixing influence microbial activity. Cold conditions generally slow biological reactions, while warm wastewater can increase oxygen demand and odour potential. FOG, rags, grit, settled sludge, pump cycling problems and poorly maintained aeration equipment can create stagnant zones. Operators should examine the complete process rather than treating odour, floating grease or poor clarity as isolated problems.

• Review changes in flow, organic load and upstream waste sources.
• Check aeration output, diffuser condition, equipment placement and mixing patterns.
• Inspect wet wells, force mains, lagoon inlets, outlets and accumulated solids.
• Compare current operating observations with historical maintenance and monitoring records.

How oxygen and bioaugmentation work together

Bioaugmentation adds selected microorganisms and enzymes intended to supplement the biological community already present. Enzymes help hydrolyze biodegradable dissolved and particulate organics into compounds that microorganisms can more readily metabolize. Under suitable oxygen, temperature, pH, nutrient and contact-time conditions, this activity can lower the biodegradable organic material contributing to downstream BOD. Inert minerals and non-biodegradable material remain.

Aeration supplies dissolved oxygen for aerobic respiration and provides mixing that improves contact among wastewater, enzymes and microorganisms. In a poorly mixed or oxygen-limited lagoon, added organisms may settle away from available substrate or shift toward slower anaerobic pathways. Bioaugmentation is therefore best evaluated as one process tool, not as a substitute for adequate aeration, hydraulic management or corrective maintenance.

Bioaugmentation performs best when oxygen, mixing, temperature, pH, nutrients and contact time support the intended biological activity.

Managing total suspended solids in wastewater lagoons

Total suspended solids include organic particles, inorganic particles and biological biomass remaining in the sampled water. Sources include influent solids, erosion, algae, disturbed sludge, grit, incomplete biological conversion and poorly settling floc. Effluent TSS can change with wind, turnover, short-circuiting, hydraulic surges, outlet location and sampling conditions, so a single result should be interpreted alongside operating observations.

Aeration and bioaugmentation can support conversion of some suspended organic material into biological floc that may settle more readily. The outcome depends on loading, oxygen, mixing intensity and the settling characteristics of the biomass. Strong mixing can temporarily resuspend deposited solids, while excessive or poorly settling biomass can increase effluent TSS. Inorganic particles are not removed through biological metabolism.

• Identify whether measured solids are primarily organic, inorganic, algal or biological.
• Inspect for short-circuiting, bank erosion, inlet disturbance and sludge resuspension.
• Balance oxygen delivery and treatment contact against excessive mixing near the outlet.
• Use representative sampling and required laboratory methods to evaluate trends.

Reducing fats, oils and grease accumulation

FOG enters collection systems from food preparation, household discharges, institutional kitchens, industrial processes and inadequate grease-interceptor maintenance. As wastewater cools, grease can separate, adhere to wet-well surfaces and combine with wipes or other debris. Deposits can interfere with floats, level sensors, pumps and piping, while retained organic material may contribute to anaerobic conditions and odour.

Lipase and related enzymes hydrolyze fats, oils and grease into smaller compounds that microorganisms can more readily metabolize. Effective reduction requires suitable contact time and environmental conditions. Emulsifying or dispersing grease is not the same as complete biological destruction and may simply move the problem downstream. Biological treatment should complement source control, interceptor maintenance, inspection and mechanical cleaning.

• Trace significant FOG inputs and enforce applicable sewer-use requirements.
• Confirm that grease interceptors are correctly maintained.
• Inspect wet-well walls, pumps, floats and downstream trouble locations.
• Adjust treatment only after considering flow, temperature, oxygen and contact time.

Sludge control and lagoon desludging planning

Lagoon sludge contains biodegradable organic matter mixed with grit, mineral solids, precipitates and other inert material. Microbial digestion can reduce part of the biodegradable fraction by converting it into biomass, carbon dioxide, water and other metabolic products. Aeration and bioaugmentation may help slow future organic accumulation or extend the interval between physical removal, but they do not make mineral solids disappear.

Desludging decisions should be based on measured sludge depth and distribution, available treatment volume, inlet and outlet conditions, effluent performance, regulatory requirements and the physical characteristics of the deposit. Operators should use a repeatable survey method and maintain mapped records. Dense grit, heavily consolidated material or excessive deposits may require dredging, pumping or another approved removal method regardless of biological treatment.

• Map sludge instead of relying on a measurement from one location.
• Distinguish recent organic deposits from consolidated or mineral material.
• Evaluate access, dewatering, transport and approved disposal requirements.
• Coordinate removal planning with seasonal flows and continued treatment needs.

Odour, hydrogen sulphide and corrosion risks

When oxygen is depleted, anaerobic zones can develop in wet wells, force mains, sludge layers and poorly mixed lagoons. Sulfate-reducing microorganisms may then generate dissolved sulfide. Depending on pH, temperature, turbulence and hydraulic conditions, sulfide can be released as hydrogen sulphide gas. Other anaerobic compounds can also contribute to odour, so not every complaint should automatically be attributed to hydrogen sulphide.

Maintaining oxygen and mixing can suppress anaerobic sulfide formation and support biological or chemical oxidation of sulfide, but effectiveness depends on oxygen demand, retention time and system configuration. Hydrogen sulphide is toxic and can contribute to corrosion after biological conversion to sulfuric acid on moist infrastructure surfaces. Monitoring requires appropriate instruments, calibration, trained personnel and procedures that recognize rapidly changing gas concentrations.

• Treat wet wells and related structures as potentially hazardous atmospheres.
• Monitor the atmosphere before entry and as required during authorized work.
• Inspect concrete, coatings, metals and electrical components for corrosion.
• Investigate hydraulic retention, septicity and stagnant zones when odour recurs.

Automated bio-augmenter dosing for lift stations

An automated dosing device can meter bio-augmenter concentrate into a lift-station wet well at selected intervals. Consistent timed application reduces dependence on manual visits and begins treatment contact before wastewater reaches downstream piping or treatment units. Contact may continue through a force main or collection system, although results depend on dose control, flow variation, wastewater characteristics, oxygen availability and retention time.

Koenders Water Solutions offers a timed wet-well dosing approach for its bacteria and enzyme concentrate. The control schedule should be based on site conditions and reviewed against operating observations rather than treated as a fixed universal setting. Any public description of patent coverage should be confirmed for jurisdiction, ownership, active status and the specific features covered before publication.

• Locate the feed point where concentrate can enter the wastewater safely and mix effectively.
• Protect the device, tubing and concentrate from weather, flooding and physical damage.
• Record refill dates, settings, pump cycles, grease observations, odour events and cleaning work.
• Reassess dosing when flow, temperature, retention time or wastewater strength changes.

Municipal lagoon aeration sizing basics

Aeration sizing begins with oxygen demand, not lagoon surface area alone. Designers and operators should consider influent flow, biodegradable organic loading, existing sludge demand, treatment objectives, lagoon depth, water temperature, elevation and the oxygen-transfer characteristics of the proposed equipment. Field oxygen transfer can differ from clean-water ratings because wastewater composition, fouling and operating depth affect performance.

Mixing is related to oxygen delivery but is not identical to it. Equipment must distribute oxygen and promote useful circulation without causing unacceptable bank erosion, hydraulic short-circuiting or solids carryover. Lagoon geometry, multiple cells, baffles, inlets, outlets and deep sludge pockets influence placement. A representative site assessment is preferable to selecting equipment solely from nominal acreage or volume.

• Define the loading basis and treatment objective before selecting equipment.
• Account for seasonal temperature and peak oxygen demand.
• Evaluate circulation throughout the lagoon, including corners and deep zones.
• Provide practical access for inspection, cleaning, repair and seasonal adjustment.

Building a monitoring and seasonal treatment program

A useful program starts with a baseline. Record lagoon levels, flow patterns, aerator condition, wet-well deposits, sludge distribution, odour locations and recent maintenance. Review required influent and effluent data, which may include BOD, TSS, pH, temperature and other permit parameters. Dissolved oxygen profiles can help identify oxygen-limited zones, but measurements should represent relevant depths, locations and operating periods.

Aeration and dosing settings should be documented and changed deliberately. Cold weather may slow biological activity, while warm periods may increase oxygen demand and sulfide risk. Rainfall, infiltration, industrial discharge and seasonal population can alter both flow and retention time. Review trends after operational changes, while recognizing that lagoon response can be gradual and affected by several variables at once.

• Establish baseline process, maintenance and laboratory records.
• Define inspection points and consistent sampling locations.
• Log aeration operation, dosing settings, concentrate use and equipment condition.
• Track sludge, FOG, odour, pump performance and compliance data as separate but related indicators.
• Review seasonal findings and revise the program with qualified technical support when needed.

Safety, permitting and compliance considerations

Lift-station wet wells are confined spaces and may contain hydrogen sulphide, methane, oxygen-deficient air and other hazards. Entry must follow the municipality's confined-space program, atmospheric testing requirements, ventilation procedures, rescue provisions and applicable occupational safety rules. Lockout and tagout, electrical safety, fall protection, biological exposure controls and traffic management may also apply to inspection and service work.

Wastewater additives, aeration changes, sludge handling and equipment installation may be subject to local, provincial, state, federal or other jurisdictional requirements. Operators should review permits, sewer-use rules, product documentation, discharge limitations and approval procedures before implementation. Aeration and bioaugmentation can support treatment performance, but they do not guarantee permit compliance or replace required sampling, process control, reporting, regulatory oversight or professional engineering review.

• Use current safety data and handling instructions for every product applied.
• Confirm chemical storage, spill response and secondary-containment requirements.
• Obtain required approvals before altering treatment processes or infrastructure.
• Evaluate performance using permit methods and representative documented data.